To Kill a Mockingbird Forum

So just to clarify, Bob attacks Scout with the switchblade that leaves the mark on her costume, and is "taken off a drunk" by Heck; and Boo comes to help already armed with his own kitchen knife that ends up in Bobs ribs, and part of Hecks cover up is his removal of the switchblade to help make the case for the "accidentally falling" on his own knife.
Or am I over complicating?

No, you have it right. Heck found the swithblade at the scene, dropped by Bob during the struggle.